(^696) „„„„„ A Textbook of Engineering Mechanics
CHAPTERCHAPTERCHAPTERCHAPTERCHAPTER
696

Transmission of

Power by

Gear Trains

34.1. INTRODUCTION

We have discussed in Art. 33.5. that the slipping

in a belt or rope is a common phenomenon, in the

transmission of power. The effect of slipping is to

reduce the velocity ratio of the system. In precision

machines, in which a definite velocity ratio is of

importance (as in the case of hour, minute and second

arms of a watch) the only positive drive is by gears or

toothed wheels. A *gear drive is also provided, when

the distance between the driver and the follower is very

small.

* A gear may be defined as a pulley or wheel having

projections on its rim known as teeth or cogs.

Sometimes, a pulley is casted with teeth on its rim. But,

sometimes the teeth are cut on the rim of the pulley.

34

Contents

1. Introduction.


2. Friction Wheels.


3. Advantages and Disadvan-
   tages of a Gear Drive.


4. Important Terms.


5. Types of Gears.


6. Simple Gear Drive.


7. Velocity Ratio of a Simple
   Gear Drive.


8. Power Transmitted by a
   Simple Gear.


9. Train of Wheels.


10. Simple Trains of Wheels.


11. Compound Train of Wheels.


12. Design of Spur Wheels.


13. Train of Wheels for the Hour
    and Minute Hands of a 12-
    Hour clock.


14. Epicyclic Gear Train.


15. Velocity Ratio of an Epicyclic
    Gear Train.


16. Compound Epicyclic Gear
    Train (Sun and Planet Wheel).


17. Epicyclic Gear Train with
    Bevel Wheels.